Interaction Between INOS and RAC2 and their Role in Free Radical Generation in Human Sepsis Neutrophils
Sepsis a complex clinical syndrome resulting from an inadequate host response to infection. Despite progress in the development of antibiotics and other supportive care therapies, severe sepsis remains an unconquered challenge for the clinicians with an unacceptable high mortality rate of 30%–50%. Neutrophils (PMNs) are important for innate immunity as well as to initiate an acute response to infection. During such a response, PMNs are activated, move towards the site of inflammation and kill the invading microorganisms, such as bacteria and fungi by phagocytosis and also by extracellular trap (NETs) formation. During phagocytosis, PMNs produce reactive oxygen species (ROS) and reactive nitrogen species (RNS) produced by inducible nitric oxide synthase (iNOS) and Rac2 (a component of NADPH oxidase). PMNs eliminate the pathogens extracellular via NETs formation composed of chromatin and granule proteins. Present study explores the interaction of inducible nitric oxide synthase (iNOS) with Rac2. We demonstrated iNOS-Rac2 interaction by co-immunoprecipitation and confocal microscopy in control and sepsis neutrophils. We found enhanced interaction between iNOS-Rac2 in sepsis neutrophil as compared to control. Furthermore we also found augmented reactive oxygen species (ROS)/ reactive nitrogen species (RNS) generation in sepsis neutrophil as compared to control neutrophil. The increased ROS/RNS was attenuated in the presence of iNOS/Rac2 inhibitors suggesting possible role of iNOS-Rac2 interaction in free radical generation in sepsis neutrophils.